Art of refining composite metals.



UNITED STATES PATENT OFFICE.

TITUS ULKE, OF SAULT STE. MARIE, CANADA;

ART OF R EFlNlNG COMPOSITE METALS.

SPECIFICATION formingpart of Letters Patent N 0. 694,699, dated March 4,1902.

Application filed January 11, 1902. Serial No. 89 ,37 6. (N0 specimens.)

T0 at whom it may concern:

Be it known that I, TITUs ULKE, a citizen of the United States, and aresident of Sault Ste. Marie, Province of Ontario, Dominion of Canada,haveinvented certain new and useful Improvements in.the Art of RefiningComposite Metals, of which the following is a specification.

My invention has reference to improvements in the art of refiningcomposite metals, and is particularly designed to extract copper andnickel of commercial purity from nickeliferous-copper material.

In the electrolytic processes of refining composite metals, andespecially nickeliferous copper material, heretofore attempted orsuggested it was the invariable practice or attempt to dissolve thecomposite metals and use the complex solutions thus obtained as anelectrolyte, to use an insoluble anodefor depositing one of themetals-say the copperso that the electrolyte eventually became sogreatly impoverished in copper as to require a considerable increase ofthe electromot-ive force for further depositing the copper, and in orderto extract all or nearly all of the copper the electromotive force hadto be increased to an inconvenient degree. In this manner the conditionsof depositing the copper varied theoretically from moment to moment andpractically so frequently as to require constant attention andreadjustment of the electrical condition to meet the varying chemicalconditions. The next step in such old processes would then be to depositthe nickel under variable and therefore commercially-impracticablechemical and electrical conditions again by the use of an insolubleanode, and this carries with it the same inconveniences as the use ofsuch anode in depositing copper. In some cases it has been suggested touse a soluble anode, such as zinc, in the deposition of nickel; but thisresulted of necessity in the contamination of the deposited metal withzinc or other metal of the soluble anode. By myimproved process I avoidthese inconveniences and render the deposition of both the copper andthe nickel practically uniform and continuous, notwithstanding the factthat for the electrolytic deposition of the nickel I also use aninsoluble anode. The uniform continuity of my process is secured in ameasure by utilizing in the deposition of the copper some of thematerial yielded in the extraction of the nickel, While the extractionof the nickel becomes uniformly continuous by utilizing in the same someof the material rejected or withdrawn in the process of the depositionof the copper. Thus in my process the depositions ofthetwo metals areoperatively connected and are in a manner dependent upon each other."

The uniform continuity of the refining process is secured not only withnickeliferous-copper material, but with other composite metals when thesame are com posed of two metals, one of which yields a compact depositfrom an acid solution with a relatively low'voltage and current densityand the other a like deposit from a non-acid solution with a relativelyhigh Voltage and current density. The most important metals of the firstorder are copper and cad mium, and the'most important metals of thesecond order are nickel, cobalt, and zinc. The composite metals,therefore,

which may be treated with particular advanunderstanding that in the moreimportant steps of the refining process cadmium would be the equivalentof copper and either cobalt or zinc would be the equivalent of nickel.

While all nickeliferous materials can be treated by my process, it is ofadvantage to employ a material that contains not more than twenty percent. of nickel and not less than eighty percent. of copper. Suchnickeliferous-copper material I cast into plates, suspend the latter asanodes in a suitably-heated electrolytea solution of sulfate of copperand nickel or of the nickeliferous-copper material and which containsfree sulfuric acid andI use sheets of copper as cathodes. By passing anelectric current from the anodes to the cathodes through the electrolytethe anodes are gradually dissolved, and commercially-pure copper isdeposited upon the cathodes. The electrolyte is kept in circulation,

Since the anodes are not made of pure copper, the electrolyte, if notrenewed, would soon become appreciably poorer in copper and richer innickel. In order, therefore, to prevent or diminish this undueenrichment in nickel and impoverishment in copper and in order to makethe recovery of these metals commercially profitable, I regularlywithdraw a certain amount of the solution for treatment in the mannerwhich I shall describe farther on. The amount of solution to bewithdrawn at any one time should be such that the amount of nickel itcontains is equal to the amount of nickel dissolved from the anode sincethe last Withdrawal. Guided by this rule, the volume of the solution tobe withdrawn periodically is readily computed by a person skilled in theart. It, for example, the anode contains ten per cent. and theelectrolyte 0.5 per cent. of nickel and the anode is completelydissolved in ten days and if the total volume of solution in circulationis six times the volume of the electrolyte in the depositing tanks, itis found that about twenty-five percent. of the solution should bewithdrawn daily. Again, if the percentage of nickel in the electrolyteis maintained at four percent. orfive percent. under otherwise identicalconditions only three per cent. or 2.5per cent, respectively, of thetotal Volume of solution need be withdrawn daily. The amount ofelectrolyte thus withdrawn is replaced by a suflicient amount of acidsolution of copper sulfate, so as to reestablish the original conditionof the electrolyte. A portion of the sulfate of copper needed forreplenishing the electrolyte is obtained as aresidue or byproduct in theextraction of the nickel, as will appear farther on. This withdrawal andreplenishment would ordinarily be done periodically; but the periods mayunder some conditions be so frequent asto make the withdrawal of aportion of the electrolyte relatively poorer in copper and thereplacement of it by an equal amount of normal solution practicallycontinuous.

The next step in my process is the separation of the two metallicconstituents from the withdrawn acid electrolyte, which, as stated, isimpoverished in copper, but richin nickel. This may be done by any ofthe Well-known or improved methods; but I prefer to do it by addingammonia (or ammonia sulfate) obtained by the last step of my process, aswill appear farther on, to the heated solution, but still keeping thelatter acid, and then cooling the solution. In this manner the nickelsalt is both precipitated and crystallized from the solution. The saltthus obtained will contain a small percentage of copper, and in order toremove all copper itis again dissolved, and the process of precipitationand crystallization is repeated until the nickel salt is obtainedpractically free from copper. The copper contained in the mother-liquoris used for replacing in part the copper deposited from the originalelectrolyte. The nickel salt obtained constitutes by itself an articleof manufacture.

The next and finalstep of myretining process is the electrolyticdeposition of the nickel. If the nickel salt is obtained as specificallydescribed, it is dissolved in water and sufficient ammonia is added tomake the solution ammoniacal. If the nickel salt is obtained by anotherprocess already in solution, this solution is likewise made ammoniacal.The ammoniacal-niekel-salt solution constitutes the electrolyte for theelectrolytic deposition of the nickel. It is preferably used hot.

In depositing the nickel I preferably use anode-plates of lead andcathode-plates ofany suitable material, but preferably one having anickel surface.

The use of lead as the material for the anodes would at first glanceseem to be impracticable, because of the formation in the process ofelectrolysis of sulfate and peroxid of lead on the surface of the anode,which former compound is soluble in ammonium sulfate. It would thus seemthat the anode would gradually be consumed by sulfatization and solutionand that the deposited nickel would become so impure by codeposited leadas to be of little value. I have found, however, that this is not thecase. I have found that the lead anode remains practically intact andthat only a'very small percentage of lead goes into the solution andbarely a trace of it is deposited with the nickel. The nickel obtainedin this manner is commercially pure.

While I have described the use of lead as the material for the anodes indepositing nickel, I do not mean to restrict myself to the use of thismaterial, since I have also obtained good results with insoluble anodesof passive iron.

As the nickel electrolyte would eventually become impoverished in nickelunless this metal is replaced in the solution and in order to preventthe saturation of the solution with sulfate of ammonia, I periodicallywithdraw a portion of the electrolyte from the nickel-depo'siting systemand recover the contained nickel salt and the ammonium sulfate orammonia, the latter being used to make the regular nickel electrolyteammoniacal. Nickel sulfate obtained from both the solutions Withdrawnfrom the copper-depositing system and the nickel-depositing system isadded to the regular nickel electrolyte periodically to replace thenickel deposited from the latter and to keep the solution of normalstrength.

I do not propose to restrict myself necessarily to the use of anammoniacal nickel electrolyte, since I have obtained good results by theuse of a heated neutral nickel electrolyte.

Having now fully described my invention, I claim and desire to secure byLetters Patent- 1. The process of refining nickeliferous-coping thenickel from a non-acid bath of the per material which consistsinelectrolytically depositing the copper from an acid solution of suchmaterial with an anode of the same material; periodically withdrawing aportion of the electrolyte as it becomes poorer in copper and richer innickel, separating the copper and nickel salts containedin the w.ithdrawn electrolyte; electrolyticallydepositnickel salt by the use of aninsoluble anode; periodically withdrawing and concentrating portions ofthe impoverishing nickel-bath, and periodically restoring to the copperand nickel baths respectively, the copper and.

nickel salts obtained from the withdrawn solutions, substantially asdescribed.

2. The circular process of electrolytically refiningnickeliferou's-copper material, which consists in depositing copper froman acid solution of that material with an anode of the same;periodically withdrawing from circulation an amount of the electrolytecontaining the same amount of nickel as is dissolved at the anode;replacing that amount'by copper by adding copper sulfate, so as to keepup the normal strength of the copper electrolyte, and recovering byelectrodeposition the nickel from the solution thus withdrawn by passinga suitable current from anodes of lead to suitable cathodes through aheated non-acid solution of the nickel sulfate first recovered from thewithdrawn solution. 7

3. The process of recovering the copper from nickeliferous-coppermaterial, consisting in dissolving such material, cast into anodes,simultaneously electrodepositing copper and regularly Withdrawing aportion of the copper electrolyte containing an amount of nickelsubstantially equal to the amount of nickeldissolved at the anode, andregularly replacing the withdrawn solution by a copper-sulfate solution,free from nickel, containing copper in the same proportion as theoriginal electrolyte, obtained from the withmaintain its normalstrength. a

5. The process of refining nickeliferous-copper material consisting inbringing such material'into solution, electrolytically recovering thecontained copper while maintaining substantially constant conditions,withdrawing a portion of the electrolyte, separating the metalscontained in the latter, returning the copper thus obtained as salt orsolution to the original copper electrolyte, and electrolyticallydepositing the nickel separated as salt or solution, from its solution,while maintaining substantially the normal composition of the nickelelectrolyte by the regular addition of nickel salt or solution obtainedfrom the above Withdrawn copper electrolyte and from the withdrawnnickel electrolyte.

.6. The process of'electrodepositing nickel with anodes of lead from anon-acid solution of nickel.

. 7.The process of electrodepositing nickel;

Witnesses:

F. T. CHAPMAN, EDWIN S. CLARKSON.

